Trump will certainly get the 1,237 delegates he needs to win the first ballot at the Convention

Trump currently has about 1,053 delegates of the 1,237 he
needs to win the nomination outright.
Republicans are still scheduled to vote in primary elections in
California, Montana, New Jersey, New
Mexico, South Dakota, Washington, Oregon, West Virginia and Nebraska
between now and June 7 – for a total of 445 delegates yet to be allocated.

It is nearly impossible to imagine that Trump will not get
the 184 additional delegates he needs to win the nomination on the first ballot
at the Convention given he is the only candidate in the race. In California alone he is almost guaranteed to
get all the 172 delegates available – delegates in California are allocated based on
whoever wins a plurality of the vote, and although there will be other
candidates on the ballot, it is unlikely an anti-Trump protest vote could
amass the votes sufficient to deny him even a single delegate. With California’s delegation almost certainly
in his pocket, he only need to pick up 12 delegates in the other remaining eight primaries to get to the magic 1,237 number. In addition to the now near certainty that
Trump will get the delegates he needs to win on the first ballot at the
Convention, Trump is helped by the fact he is now the “presumptive nominee,” which
means his campaign will take a central role in planning the RNC
Convention. That doesn’t mean he will
completely control what happens at the Convention – but he will have a definite
say in how things are run – making it that much harder for anyone opposing him
to gain traction at the Convention.